This section provides background information related to the present disclosure which is not necessarily prior art.
Electronic equipment often generates electromagnetic signals in one portion of the electronic equipment that may radiate to and interfere with another portion of the electronic equipment. This electromagnetic interference (EMI) can cause degradation or complete loss of important signals, thereby rendering the electronic equipment inefficient or inoperable. To reduce the adverse effects of EMI, electrically conducting (and sometimes magnetically conducting) material is interposed between the two portions of the electronic circuitry for absorbing and/or reflecting EMI energy. This shielding may take the form of a wall or a complete enclosure and may be placed around the portion of the electronic circuit generating the electromagnetic signal and/or may be placed around the portion of the electronic circuit that is susceptible to the electromagnetic signal. For example, electronic circuits or components of a printed circuit board (PCB) are often enclosed with shields to localize EMI within its source, and to insulate other devices proximal to the EMI source.
As used herein, the term electromagnetic interference (EMI) should be considered to generally include and refer to both electromagnetic interference (EMI) and radio frequency interference (RFI) emissions, and the term “electromagnetic” should be considered to generally include and refer to both electromagnetic and radio frequency from external sources and internal sources. Accordingly, the term shielding (as used herein) generally includes and refers to both EMI shielding and RFI shielding, for example, to prevent (or at least reduce) ingress and egress of EMI and RFI relative to a housing or other enclosure in which electronic equipment is disposed.
Nowadays, printed circuit boards (PCBs) are widely used in the electronics and communications devices, generally as substrates for mounting of electronic components. The PCBs generally include one or more layers of an insulating substrate on which an electrical circuit is formed by depositing a predetermined pattern of a conducting metal (e.g., copper, etc.) for connecting various electronic components (e.g., semiconductor components, etc.), which are mounted on or embedded in the PCB layers. Such electrical circuits include components which can operate at a high radio frequency (RF). The RF emissions from these components may interfere with proper operation of other components or circuits in the vicinity of these components on the PCB. In this case, it is important to shield these RF emissions in order to prevent RF interference. In addition, it is also possible to shield these RF emissions in order to prevent RF interference to some components or circuits.
For compact electronic devices, such as radiotelephones, a PCB serving as a ground plane may be utilized as a part of a shielding system. An electrically-conductive housing (generally referred to as a “shielding enclosure”) that is configured to surround a part to be shielded is generally secured upon the PCB.
Considering a miniaturization demand of the electronic devices, a size of the shielding enclosure, especially, a height above the printed circuit board, is restricted. Therefore, the inventor hereof has recognized a need in the art for a shielding enclosure having a height as low as possible.